1. Field of the Invention
The present invention relates to a resistor which hardly causes dispersion in resistance value, has excellent environment resistance such as moisture proof, and has increased power capacity.
2. Description of the Background Art
In general, a cermet resistor is widely known as a resistive element having high accuracy in resistance value. In order to manufacture such a resistor, resistive paste containing an Ru oxide or an Ru compound is printed on a surface of an alumina substrate, for example, to form a thick resistive paste layer, and this layer is fired at a temperature of 800.degree. to 900.degree. C. to form a resistor film. Then, glass paste is applied to a surface of the resistor film provided on the alumina substrate and fired to form a glass film, thereby improving resistance to the environment, such as moisture proof, of the resistor film.
In such coating of the glass film, however, the resistance value of the resistor film is easily changed to cause dispersion of characteristics. Further, the glass film may contain pinholes, to cause deterioration of the resistance due to penetration of moisture etc. in a high-humidity atmosphere. In addition, the resistor film is inferior in adhesion to the substrate since the alumina substrate, the resistor film and the glass film are all different in thermal expansion coefficient from each other in the aforementioned resistor. In the conventional resistor, therefore, it is impossible to obtain high power capacity so that the upper limit of obtainable power capacity is 100 mW.